CryptographicException error on logout

Recently, we've migrated a web application using .NET 1.1 to a .NET 3.5 environment. I began creating a new set of simple tests to check performance--the test simply logs a user into a site, loads an item into view, clicks several tabs, and then logs out. Upon playback, nearly invariably, i'm getting the following error on the logout page...

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace:

[CryptographicException: Bad Data. ]

Does someone know how I could have WAPT ignore this error? My users are all successfully logged out of our site, but because of this exception, i'm unable to tell an otherwise good test result from a bad one without inspecting all errors within the log.

This problem is much spoken about on the Internet. Most probably, it is connected with upgrade of .NET. Please search for corresponding discussions, there should be some pieces of advice regarding elimination of this issue there.

This problem is much spoken about on the Internet. Most probably, it is connected with upgrade of .NET. Please search for corresponding discussions, there should be some pieces of advice regarding elimination of this issue there.